I. Field
The present invention relates generally to electronics, and more specifically to a diversity receiver for wireless communication.
II. Background
In a wireless communication system, a transmitter modulates data onto a radio frequency (RF) carrier signal to generate an RF modulated signal that is more suitable for transmission. The transmitter then transmits the RF modulated signal via a wireless channel to a receiver. The transmitted signal may reach the receiver via one or more propagation paths (e.g., a line-of-sight path and/or reflected paths). The characteristics of the propagation paths may vary over time due to various phenomena such as fading and multipath. Consequently, the transmitted signal may experience different channel conditions and may be received with different amplitudes and/or phases over time.
To provide diversity against deleterious path effects, multiple antennas may be used to receive the RF modulated signal. At least one propagation path typically exists between the transmit antenna and each of the receive antennas. If the propagation paths for different receive antennas are independent, which is generally true to at least an extent, then diversity increases and the received signal quality improves when multiple antennas are used to receive the RF modulated signal.
A multi-antenna receiver conventionally has one RF receiver processing path (or simply, “receive path”) for each receive antenna. Each receive path includes various circuit blocks (e.g., amplifiers, filters, mixers, and so on) used to condition and process a received signal from an associated antenna. The circuit blocks are designed to meet various system requirements such as linearity, dynamic range, sensitivity, out-of-band rejection, and so on, as is known in the art. In conventional diversity receiver designs, the receive path is typically replicated for each receive antenna. The replication of the receive paths with identical circuitry results in higher power consumption, larger area, and higher cost for the multi-antenna receiver, all of which are undesirable. For a portable wireless device, the higher power consumption adversely impacts standby time and reduces talk time between battery recharges.
There is therefore a need in the art for a low-power diversity receiver.